Comment 1 for bug 1681831

commit 13a2ed432a23ed51203df9d158a0316ea0f427c6
Author: Krunal Bauskar <email address hidden>
Date: Wed May 3 11:01:21 2017 +0530

    - PXC#816: Regression in GTID consistency when parallel applying used for async replication

      - GTID event generated from MASTER is processed by SLAVE.
      - SLAVE can process this event using master-thread if slave-parallel-workers=0
        or assign it to slave worker is slave-parallel-workers > 0.
      - Starting 5.7, MySQL has stopped writing this event to bin-log but PXC need
        this event for proper creation of write-set so PXC has logic to cache this event.
      - Hook to cache this event was wrongly placed that was triggered only if
        GTID event is being processed by master-thread (that is slave-parallel-workers=0)

      Fix:
      - Corrected hook such that the thread that is processing this event will
        cache the event.